How to test a bad knock sensor. EASY FIX !!
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- Опубликовано: 12 окт 2015
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In this video I talk about an easy way to test the knock sensor 
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**Want to own the tools I use ?? Click on the amazon link below to get my top 5 Tools I use**
Automotive Test Light- amzn.to/3z1Pdxa
Flexible Backprobe- amzn.to/3Pyr3zO
Multimeter- amzn.to/3PbuT23
OBD Scan Tool- amzn.to/3zaNWnq
Wire Piercing Probe- amzn.to/3OecWhT
When you bench test the sensors from the prong to the case, the O.L means open line, which means infinite resistance, not 0 resistance. When you read a small resistance it means the electricity is able to flow, meaning there is a short within the sensor. Just to clarify for all readers, good sensor = O.L (infinite resistance), bad sensor = any resistance reading. Cool demo of them installed though, still very useful overall.
Thanks and good explanation. First time I’ve had this problem, 05 Chevy with 600k miles.
How that is a lot of work!!!!! I am going to have my buddy sit and watch taking pics... and my girl cleaning parts... Thank you! I used to work on Chevy's 65-76 This is a whole different animal!!!!
Great vid man. Thanks for your time 🙌🏽
Thanks for the info I am not a mechanic but like to work on my vehicles with some solid info like this more condfident on what we are doing best Regards.
Thanks for explaining things with ease. I was trying to figure out if I could solve the problem on my own...apparently not. I need the tools to get to the knock sensors first. But at least your video helped me understand what's going on and what's going wrong and why
thanks for watching and supporting my channel!
Thank you! I was able to follow along and understand, having used VOMs before and done light car mech work. Researching potential issues for next car I want to buy.
Liz L. Check out my new video it's another recap on the knock sensors
As you asked me how I did. I'm love mechanic job and tried to do like DIY. My Multymeter just only use for house so I got failured for resistance testing. I almost bought new one with high Ohm (20 M- 200 M ohm ) and I already finished to resistance test and installed the knock sensors for my friend's Toyota Sienna 2001. Everything was fine. I just found out you have your RUclips channel. I'm very interesting with that. I thing I'll learn more to DIY by your video channels. Again I'd like to say thank you to your useful video that you did very good job more than others I watched on RUclips
thank you for watching. I really do enjoy when I help others. makes me feel like im impacting them.
Nice and clear description - Just tested two sensors following your details - Nice thankyou
Thanks so much, great video super helpful you explained everything simply without complicating. Gettin out my multimeter..
Great video. Very clean and to the point. Not all the typical bs..... remember to use jack stands, eye wear etc.... A++ Props bro.
hey thanks for watching. and bringing in the good comments
Thanks bro,you helped me alot👍🏽👍🏽👍🏽
Thanks for the video. Great explanation. Nice to see how it works.
Great video. Very informative.
great info I have seen the knock sensors bad right out of the box brand new so test your new sensor with ohm meter before you install it will save a lot of hassle I just did one and customer was told it was the wiring that was the problem when the other shop just installed the sensor without testing the new one and it was bad.
good advice bro... mines hiden Under my intake manifold...need to pull the manifold to replace..wish it were as easy as urs
6 years later this helped me. Bless🙏🏼
7 seconds in and you're good in my book. let's go TEXANS!!!
BK Johnson lol got to love my Texans
thanks good lesson,out at reading Pa
Thank you! My son-in-law just called earlier. His 2003 avalon codes point to bad knock sensors. I just got done reviewing the work involved. I'm still in shock.
From what I've heard, the cable is more likely at fault due to damage from heat. But, while it's opened, it's best to replace sensors and cable $$$. Might replace the antifreeze cross-over, too. What else can be done as long as all that stuff is out of the way? Plugs?
Great Video!
Good job. Nicely done.
great video very usefull! subscribed
Great! Thank you
Great one shot video I learned something new so I subscribed
does a 2001 chevy impala have 2 knock sensors. im getting a p0327 code
I have a question, I have a 2000 Toyota Solara 3.0 v6 I had a diagnostic test and the code for knock sensor. So I changed both knock sensors and wire harness. I test drove after and less than five miles the engine light came on again. I took it right away to have another diagnostic test done and it read the same code. What could it be ?
thanks for the help bud! subscribed
thanks for subscribing
Javan Trinidad 193 Toyota camry
Hi, I have a question about a knock sensor possibly bad on my 2012 Chevy Cruze. We just can't figure out what's wrong with my car.. What does your car do if you have a bad knock sensor on a Cruze Eco?
what cities does emmissions testing apply to
Good to see a good repair rather than a hack. Thank you. The knock sensor is a microphone that listens to your engine and makes real-time adjustments to the ignition timing and fuel air mixture to maximize fuel burn for optimal fuel economy and emissions. It keeps the engine balanced and an out of balanced engine pollutes more and wears out much faster. I recently replaced both knock sensors on a 2002 RX300 and it is not that big of a deal for a mechanic. i very highly recommend to buy premium knock Japanese sensors, not the aftermarket junk from China. During the test drive I has able to register 28 mpg on a 19 mile run, much better than the 16 mpg it was getting with the engine running in "fail-safe" mode with the bad knock sensor. Compression test on all cylinders showed 192-198 psi at 223,000 miles. I expect the engine to make 500,000 if properly maintained. Again thank you for not posting a knock sensor hack.
I have a Pontiac G6 that's pinging real bad I got to put a really high octane in it to get rid of it but it's still a little bit there I don't have any engine codes I was wondering if you think it might be a knock sensor that's not showing up on the scanner
Can the banging fruition a bad motor mount give false signal to the knock sensor.
Nice to know for future. thanks for your post
Bought a motor for our 2002 Toyota Camry online engine was from Japan. The car we have was built in the US. The engine went in no issues but the nox sensors had a different number of pins and the two were not interchangeable. The car is throwing a P0325 code. Not sure what to do.
The resistance of knock sensor on my opel vectra a referred to car body is 285.7 Ohms. The voltage within connected to sensor wire is 8.75 V(engine runs), the voltage on disconnected to sensor wire is 10.18 V. Is the sensor corrupted/shorted?
hey....i hope you can help me! i got a Pontiac Firebird 5.0 TPI with Code 43, Knocksensor, ESC Module....ESC is in Chipset included not a seperate Box. The ECM is a delco replacement. Car is stuttering from Idle to 2000 rpm when i pull fast WOT. Up from 2000-5000rpm engine runs fine. Knocksensor works! Car runs rich and smells unburned gas. Any Ideas? Best regards from Germany
Thank U Big help
Good job thank you.
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My 2002 wrx nock sensor rip the switch on the motor culd i just plug it streight
So, why did you use AC voltage and not DC voltage on the multimeter? Cars use DC mostly and the only AC is in the alternator before the regulator changes it to DC. Just trying to learn my one thing for today. Thanks! Good, informative video by the way.
Ox The knock sensors produce an AC voltage signal from this noise.
I see - very interesting! Thank you for your response. Subscribed.
I guess then, that technically modern vehicles produce 2 sources of AC voltage - 1 in the alternator ahead of the regulator and 1 in the knock sensor(s), although it's in milliamps! lol
Feel free to check out my new video on knock sensors
I heard the ECU actually looks at the frequency of the voltage produced by the knock sensor. Some newer knock sensors are tuned to a specified frequency like 7Khz. Unlike the older designs which respond at all frequencies of motor vibration. 7Khz I guess is the magic frequency of engine knocking. What throws me off with this concept is I would bet that many engines might produce vibrations in that range when revved to certain rpm without even any actual engine knock occuring. I would like to know what the circuit design on the ECU side is for knock sensor circuit.
Here is an interesting note for testing older ones. The older knock sensors measure a specified resistance. That needs to be fairly narrow range of ohms for the circuit to work. You can check that as shown in this video. On my 1997 Nissan Maxima. I found a plug connector on the engine harness which the knock sensor wire passes through. My sensor is under the intake manifold and a lot of trouble to access. Easy way is to turn off the engine and unplug the harness connector then measure the ohms from sensor to ground. It should read as specified in your manual. Mine was approx 500Kohms. The reason this test works is because one side of the 2 wire sensor is grounded on the block. Then measure the resistance of the ECU side of the connector to ground(with key off). Notice that it has nearly the identical resistance as the sensor? Yes its a voltage divider circuit. I suspect this is for "impedance matching". Same as audio circuits. Maximum power is transferred with the input impedance matches the signal source. This makes the circuit more sensitive to the signal which is weak since it is just produced from a peizo-electric device.
If you look at a simple signal amplifier circuit. It uses a voltage divider (2 resistors in series to create a "bias voltage" at the input to a power transistor (usually the base of an NPN or PNP bjt transistor). This is just my speculation.
Anyhow usually the sensor resistance to ground should be very close within 50- 100ohms of the ECU side resistance to ground.
Another way to test these from Eric the Car guy as instructed by his friend @ Wells Electronics(they make knock sensors) is
1) unplug the knock sensor harness,
2) turn key on measure volts on ECU side should be 4-5 volts range)
3) plug in sensor to harness
4) back probe harness connector( key on careful not to short to ground) with a wire pin or paper clip or use piercing probe to pierce wire for sensor.
5)measure voltage. It should be approximately half what it measure open circuit with the sensor disconnected. This is correct voltages. It demonstrates that the circuit is setup as a voltage divider with equal resistance on ECU input and Sensor side of the circuit.
5) the small a.c. millivolt signal generated by the knock sensor from engine vibrations rides on this small DC voltage usually 2-2.5 volts into a signal amplifier and probably a bandpass filter circuit which selects only frequencies in a specific range I.e. 7Khz as mentioned before. Some new knock sensors have the filter built into the sensors, so wacking the block with a hammer may not actually produce any measurable millivolt ouptut from the sensor unless its in that frequency range.
However this is all very interesting...
NOTE 2: did you notice the knock sensor wiring has a grounded shield jacket over that piece of harness running to the sensor? Yes. The short section of wire harness is special. The shield wire travels back through the harness to chassis ground. This is used to provide a "drain" path for "induced voltages" caused by EMF interference from other electronics on the engine like the ignition coils, the starter, the alternator etc. Those other devices and even your cell phone produce radio noise which can induce high frequency voltages onto the knock sensor signal wire. The grounded shield is important.
So a complete diagnosis of knock sensor problem includes measure ohms of sensor, voltage from ECU and ground on the shield wire. If the sensor ohms are not in proper range and/or the voltages are not as expected from the ECU then you have to do continuity tests on the harness to find or fix any shorts or open circuits in the harness.
Therefore: You should also test the wiring and harness to verify that the shielding side has continuity to ground and not shorted to 12volts etc. This shield is equally important so your engine computer is not retarding ignition timing sporadically from false signals that are not actual engine knocking. This probably would not set a code unless it was really severely hurting engine performance. However it will reduce engine power and economy if timing is too retarded and not optimized.
I would like to see someone (like Scanner Danner) demonstrate a test/measure of knock sensor circuit using an oscilloscope. Also wondering if OBD2 code scanner can monitor real time knock sensor wave form like they do for o2 sensors
Milliamps is not a Voltage, it is current. The meter reads this current and converts that value to a Voltage by the internal resistor in the meter, only current can deflect the meters' needle. This is why you never check live voltage with a meter on an Ohms setting.
Great video thanks
Thanks for watching. Don’t forget to press the notification bell on my videos to receive all the new videos coming out.
mr how u can help me whit my toyota 3.0 6 cilinders 1989 knock sensor is bad,i need to répleset engeneligth show up?
Question? I have a 2003 hummer h2. What is the knock sensor voltage required? my multimeter says 5vlts is that ok ...
great video, very informative....question though: "Why set meter to AC volts and not DC volts?"
Supplied voltage ac by the knock sensor same as crankshaft sensor
I diagnosed my Toyota Corona st191 and it shows an error code 52 which is the knock sensor. Question, is this the root cause of my problem when hitting my accelerator when driving it shows the check engine light but when I don't, it doesn't show up? Also when I turn on the A/C, engine slowly looses power until it stalls. Hope to get some answer to this and thank you very much.
same for 02 crv 4 cylinder?????
hi. I have a question. I have an 01 xterra. it started to idele pretty hard and I stopped at the light and it stalled. I've changed the plugs, wires, distributor but even tho it sounds better its still not running properly. only seems to start after the car warms up a little bit. do u think it could be this ? where would u recommend I look next?
Check your fuel pressure.. never mind your comment is 3 years old
Pretty helpful
08 sonata 3.3 po326
Anyway to do that first test with sensors installed.... I don't mind doing the job just gonna take a while getting gaskets and tools together
Thanks
I have suzuki alto 2002 and knock sensor light on off. And engine making knocking like tarrr tarrr. I have changed 7 knock sensor but still that problem. And the wiring till computer is ok
thx for posting video one of mine was bad
+tino8080 hey man thanks for watching
hi there OZ. i got P0325 Knock Sensor 1 Circuit Bank 1 or Single Sensor. i change the knocking sensor "brandnew" but the code still there..
i dont have any idea what happening on my car..
Thanks in Advance
Honda CR-V 2002
We have a 2001 Toyota Sienna, using a multi-meter to check the knock sensors. It's a Craftsman multimeter and there is a section for ohms, but you also have to choose between 200-2000k, do you know what setting I have to put it on?
20m
Donde va ubicado exactamente gracias
Can a knock sensor trigger other codes on a toyota 3vz?
thanks oz
no problem thanks gor watching
how many knock sensor does my lexus 2000, es300 has? Thanks for your informative video.
Your car has the 3.0 V6, so it'll have two, one for each bank.
What about Honda Civic 1999
I live in riverside for how much will you replace my spark plugs on my 2007 G35 automatic, I also want my coil packs checked as well as my knock sensor replaced or inspected, you seem to know what your diong becuase I don’t trust mechanics at all, as I have been ripped off before in the past but I now know what to look or inspect due to a lot of research.
I live in Houston tx by the way
TY Oz, nice explanation on these things
Gary I just made a video today that Explains more. Should upload by tomorrow
cool thanks, I just replaced my sensors and harness but bank 2 coded again. I think I may have made the mistake by using duralast sensors but this method you explained on testing will help me determine that for sure.
Gary on what car was it on ?
05 gmc sierra 2500 w\6.0
Gary well the new video I just did was on a 06 Silverado. And it explains how to test it on the vehicle
my engine would knock at 3400-4000 it sounds like something was loose but then I installed an aftermarket ecu and now it knocks from 3400 to 6000, so was my knock sensor bad this whole time it never through any codes
Ur motor was know good lol threw a rod bearing
I replaced both and the harness. Had a code for bank one sensor one. After clearing the code drive great for 5 days. Pops back up with bank 2 sensor 2. I already replaced..so I'm sorta lost any sugestions
whats the yr make and model ?
Oz Mechanics 99 lexus es300
defective knock sensor or bad conection check the continuity on the wire if ok replace the sensor
maxnguyen22
did you use aftermarket sensors? i have to do this same job soon and every time i try an aftermarket sensor it throws lights on the es300. use actual Lexus parts and see what happens, did u fix it yet?
i have a 2001 dodge stratus and when i turn it on it makes a ticki g noise especially when i accelerate it what do you think this can be?
Letty Ayala I would check the oil first
I have a 2001 Lexus GS430... My check engine light is ON due to a bad knock sensor. My mechanic recommended to replace both sensors. Including the wire harness attach to it. He said it would take half a day for these type of work and is charging me about $1,000 for both labor and parts. Why do you think?
dxraaaaa make sure it's all oem parts. Lexus/Toyota knock sensors are no joke they are stuffed in the engine compartment. When I change them out I normally have to change out other seals and gaskets due to removing the intake manifold, injectors , throttle body just to get to them. Jobs are normally expensive but just ask him to tell you to break down exactly what he's changing out
thanks👍👍👍👍
thanks
Hey, on the knock sensor, the end that is threaded is it open or closed?
The threaded is closed.
does anybody know how to tell which sensor is which i have what the scanner gave me but no exact location which is which. also after removing the intake manifold do u have to use a new gasket when putting back on
billy self by inputting the code online you could find out what bank it is example bank 1 or 2 and yes please change out the gaskets
Thank you..
+MrCarzonekit thank you for watching
Hello, i have s problem with my vehicle i have a 2000 Silverado and my knock sensor keeps coming on I've replaced it twice but still say 1 sensor low as well as my mass airflow sensor which got replaced by a mechanic but still get po122- Po 123 and knock sensor if you could help me out
Que pasa si el problema sigue le chequeo todo eso y nada q se soluciona el problema
This car has 2? Do all cars my code is sensor low input bank 1 so guessing I have 2 As well...
Can’t find a video with a 2003 saturn vulture 4 cyl
replaced both knock sensors and harness on my 2000 Silverado. knock error still comes on for bank 2. how can I check what's wrong?
did you clean out where he knock sensor reside? most times is full of rust or minerals
I have a 2004 Suzuki i just replace a use engine i herd the lfters . but the engine 💡 light on.. Say that it need. The nock sensor to replce.. Should i replace it.. Please
on 2005 suv Ford crank shaft sensor v6
Great , easy to understand , Juan F.
Knock sensors rarely go bad they usually throw a code along with something else that causes a knock like for example bad injectors .alot of shops tell you that you need to replace the knock sensor just to get your money
That’s why diagnosis are done to prevent throwing the parts canon. Well the knock sensor that go bad a lot are on the 5.3, 6.0 chevy engines
Oz mechanics,I wasn't directing my comment at you,I'm not saying you're ripping people off.
What I'm trying to say is if your knock sensor throws a code it doesn't always mean it's bad if there is another code with it like for example open circuit on injectors the problem is the injectors.fix the injectors and both problems are solved.the knock sensor will no longer detect an engine problem and won't throw a code.once again,knock sensors rarely go bad
Yea no problem.
Very cool ....thanks
my knock sensor was replaced with a new on and the check engine light keeps coming on for the knock sensor, how do i chick the harness?
thanks
TomBrady's shirt what's the yr make and model ? Did you change out the wiring harness as well
A circuit diagram from repair manual will help A lot. But if you dont have a schematic with pinouts for the harness plugs you can do some quick testing right at the short plug at or near the sensor.
1) make sure the engine has a good ground to chassis and battery negative. Same for your engine computer. Check that but has a good clean ground point with low resistance to ground (measure with ohmmeter)
2) unplug sensor from harness
3) measure ohms on sensor signal pin to ground. Should be approx 500kohms on most cars
4) turn on key and measure voltage on the harness plug for the sensor. It should be approx 4.5-5 volts on most cars
5) if you you have 4.5-5 volts that is a good sign. If it's much higher its shorted to power somewhere. If its very low or 0 volts its likely shorted to ground or open circuit (broken wire or loose plug somewhere)
6) If the signal wire to ECU measured good then check the shield wire is grounded to battery negative
7) other way to test harness for shorts or opens is unplug ECU and if you know the pin or wire location on the ECU plug you measure resistance all the way through to the sensor. It should be close to 500Khms. Also can check to shift to ground with ohmeter there. This is why a good manual is needed with harness pinnout diagram and wire color codes. It helps you know where to measure with your test meter.
3) if all the harness tests are pass then possible the ECU has issues. ECU can be damaged with cheap test lights and also cheap test meters. Make sure your testers are rated safe for ECU or it says 10Mohm input impedance on the meter or Hi-Z that is short for high impedance. It will not damage the ECU electronics why shorting to ground or power through a low resistance meter.
My car stalls a lot and sometimes shut off in traffic , could this be the problem ??? I got a diagnostic at autozone says knock sensor are they accurate
DaCamper Noob i never seen a knock sensor to cause a stalling problem
Thank u so much from algeria camry mzfe
Do you know what torque to use when mounting this knock sensor ? My engine knocks at 2000rpm and I suspect this sensor. It's not the same design, it's like a doughnut with the screw in the middle!
Sounds like a gm one . What's the yr make and model
It's a VW GOLF mk4 1.4 16v engine, 2001!
Symptom bad Knox sensor
15 lb ft
I tested a new one on Ohm voltmeter and got nothing to read! What's wrong with it?
make sure the ohm meter is set on the right settings
I saw your video on ohming out knock sensor. I got Chevy Silverado 5.3 vortec. I need some knock sensors because my check engine light is on. I replaced them once and check engine light never went away. I ohmed them out and they read 100k. I put a different setting on meter for continuity and read ol. These knock sensors are from O’reilly auto parts. What do you recommend I do? After market or original? Some say Chevy needs original parts. I don’t know. Suggestions?
Whenever I do the Chevy knock sensors I make sure to always use ac delco. You're welcome to watch my newer knock sensor video. It's on a 5.3 engine Robert Munguia
Changing the setting on the meter only means you had the setting too low, so the meter read Overload (resistance was out of range for that setting). I don't know what the reading should be but I would guess the sensor is ok.
Your in Pasadena md?
Pasadena, tx
I got a knock sensor from Napa brand Napa it was 120 plus tax. Nock wire from internet you think I'm safe a Napa senser new wire or do I have to have Toyota knock?
George Cates when it comes to knock sensor I prefer to use dealer parts
Thx u
How much do you charge for this job ?
how do you check the knock sensor (in circuit) on a 2004 infiniti g35?
meaning if you can't see it on the engine, where are those plugs/wires?
angelisone Ever figure out your problem?
Yes, but sad news.
Defective left valve cover (Japanese is building cars like American) and transmission is slipping.
Valve covers are made out of cheap plastic.
Spark Plugs Tubing Gasket is fused into the cover.
Will a Toyota L4 1.8l run with the knock sensor disconnected?
should run with the knock sensor disconnected. normally most vehicles do
Do you have a picture of the wire to disconnect from the "brain"?
It'll run but not very well. It also won't prevent knocking which will cause serious engine damage.
My check engine light came on so I went to see what was wrong with the suburban...it read knock sensor bank1 so I replace bank1 and bank2...a couple days later the check engine light came on again sayin bank2 so the auto store gave me a different one thinking it had a defect changed it then again a couple days later the check engine light came on again sayin the same thing bank2...do you know what could possibly be causing it
I have a newer video showing the procedure on the chevys. But I always change out the sensors with original one plus the wiring harness. And also make sure that the matting surface on doesn’t have any rust
CAN CHEAP KNOCK SENSORS MAKE IT READ THAT A KNOCK SENSOR IS BAD...I CHANGED THE WIRE THAT PLUGS INTO THE KNOCK SENSOR AND THE CHECK ENGINE LIGHT CAME ON AGAIN AND SAID BANK2 AGAIN...
Oz I thought if the knock sensor read nothing that it is bad I thought It should be around 100-105 ohms????
Would this work if I’m getting the universal knock sensor malfunction seeing the same amount of knock every time no more no less and code just keeps popping up it’s on a 2g Dsm eclipse gst
I see the same amount of knock 3.2 degrees every time no more no less
Nick Tunes idk braddah u gotta try um yourself cannot be asking everytime
Justin Jones asking what every time I have a knock sensor malfunction with multiple knock sensors replaced so I’m trying to see if it’s my harness and if I’ll have to wire straight to ecu it’s self.
Nick Tunes shit idk just do um I no care
Justin Jones ??? I’m not sure we understand each other brother sorry for the confusion
Hey Oz are u in Pasadena i think u help me once years back by preston...i need help brother where u located now
Hi is there suppose to be a change in resistance upon touching and then no resistance whatsoever
no resistance is a bad knock sensor.
+Oz Mechanics so I should get some reading
+Oz Mechanics I have the knock sensor out of a used motor so I wanna make sure before I replace it
+Salman Ghani yea just test the resistance
+Oz Mechanics ohk I did the resistance check and when I touched it with the probe it went to around 300 and then back to 1
i changed both knock sensors and both sets of wires and still have code and symptoms.. any ideas i would really appriciate it
Gilberto Mendoza on what vehicle is it on. And did you use original knock sensor?
Oz Mechanics 05 suburban and i think i did not use the oem
Gilberto Mendoza ruclips.net/video/9VRBJ1Jn_gU/видео.html
Make sure to clean where the KS go
Oz Mechanics i saw the video thanks. ill try that as soon as i get a chance. do you recommend getting new parts all around (oem)?
i grinded alot of rust or whatever it is from the hole but does it have to be 100% clean? the reason why im asking is because my dremmel wont reach all the way down there
Cost for replacement? Plus labor?
Thanks for the vid.
Brandon Murphy id like to know as well
DOES TOYOTA KNOCK SENSOR WORK ON LEXUS RX300
THANK